Ozone depletion is one of the hot button issues of environmentalism and has caused massive changes in the way we do things over the last fifty years.
The biggest problem is that for many people, ozone depletion is something of a buzzword: it makes for a good soundbite although few people actually understand the causes or the concerns other than a general sentiment of it being a bad thing.
Fortunately, it’s easily measurable and understood, allowing even the layman to make choices which will help to keep intact this vital part of our atmosphere.
Understanding the Ozone Layer
Our atmosphere is comprised of several different layers, all of which are essential to life as we know it functioning. Quite far above the surface of the earth, at the upper limits of the stratosphere, the ozone layer resides.
On ground, this tri-particle allotrope of oxygen gas is pretty nasty on life. It’s a heavily oxidizing agent, allowing it to do extensive damage to living things, but it has a little secret when it’s placed up high: the ozone layer blocks out the majority of the UV radiation which is emanated by the sun.
The concentration of ozone is actually quite small, even at it’s highest concentration, it reaches only 2-8 parts per million. It’s created at this level by the ultraviolet light it keeps from coming to Earth.
The intense ultraviolet radiation blocked by the ozone layer hits diatomic oxygen, the usual stuff we need for our respiratory systems, and causes it to split. These free oxygen particles then unite with another segment of O2 and form ozone or O3.
Ozone then absorbs ultraviolet radiation in the 200nm-310nm or so. It accounts for taking up most of the harmful UV-B radiation which comes to the planet’s surface, while the extremely harmful UV-C radiation is primarily blocked by normal dioxygen.
What does this mean?
The 90%+ absorption of the 200nm-310nm range of the ultraviolet spectrum is absolutely essential for human life.
At the end of the day, the ozone layer isn’t something convenient for life… it’s one hundred percent essential.
Causes of Ozone Layer Depletion
Unfortunately, the ozone layer isn’t nearly as stable as was previously thought. Human actions can have an enormous effect upon it in its entirety and due to upper stratospheric currents, the lack of concentration tends to pool in certain places.
Those would be the “holes” in the ozone layer which were a common illustration some years ago.
The causes for this lowering of ozone levels have been quite well studied over time, and measures have already been enacted against them in most jurisdictions.
Chlorofluorocarbons
Chlorofluorocarbons are the primary culprit of ozone depletion. For many years they were used in both refrigerants and aerosol cans, which had decimating action in a relatively short amount of time.
The primary chemical action by which this occurs is through the release of chlorine, which interacts with ozone and binds it into chlorine monoxide. This action can then be repeated for quite some time, with the chlorine monoxide interacting with another ozone molecule and resulting in free chlorine and an O2 molecule.
Acting as a catalyst, a single molecule of chlorine can then interact with and destroy ozone molecules for up to two years before it is removed from the cycle.
As we noted above, concentrations of ozone are actually quite low overall which means that even small amounts of these gasses can, and do, effect a lot more than it would seem at first glance.
One of the most commonly repeated myths about CFCs is that since they are denser than air they’re unable to reach the stratosphere in the amounts needed to cause problems. Unfortunately, this isn’t the truth or these problems wouldn’t be occurring.
Halons
Halons have some serious ozone tearing potential, but thankfully their usage is extremely restricted. The only current large-scale usage of these chemicals is in specialized fire extinguishers.
Continuing Problems
Unfortunately, there are likely to be continuing problems for some years to come, even if the use of CFCs were to be phased out entirely: the life cycle of these chemicals within the environment can be measured in decades so all of those released are going to continue disrupting the ozone cycle for some time to come.
Currently it’s estimated that roughly 80% of the depletion of the ozone layer is through CFCs, with almost all of the remaining 20% being attributed to other man-made causes. While chlorine and bromine do effect the ozone layer in their natural form, it’s estimated that at most 2% of the damage done has been through natural sources of these elements.
The 90%+ absorption of the 200nm-310nm range of the ultraviolet spectrum is absolutely essential for human life.
While it’s hard to estimate just how much further damage is going to be done, the truth is that the usage of CFC chemicals is now so tightly regulated that it’s entirely possible that most of the damage caused by them is going to repair itself over the coming decades.
That isn’t to say it’s entirely not a problem: while heavily punishable with fines there is still a lot of uncontrolled release of CFCs, especially within the HVAC/R field where it’s technically forbidden to release more than an ounce or two of the gasses but often more expedient for technicians to just “off-gas” a system.
There is also the possibility of complete failure of the pressurized systems which contain refrigerants. Larger commercial systems can contain extremely large amounts of these gasses and a single burst fitting can cause the off-gassing of the entire pressure system in a matter of minutes, while slow leaks can still unleash large amounts of the gasses over a slower period.
There has been a lot of progress in this area, however, as HCFCs are rapidly replacing most of the traditional gasses used in refrigeration and older systems slowly begin to phase themselves out.
The elimination of CFC as an aerosol gas has also been a major help since the average consumer no longer has access to these ozone-depleting chemicals.
There’s another major factor, of course: climate greatly affects the location of “holes” in the ozone layer. Colder places tend to receive more damage and stratospheric currents generally trend southwards which is where the most famous damage has occurred.
The climate and atmospheric conditions above Antarctica have a tendency to trap ozone-depleting chemicals in one area, concentrating the damage and thinning out the concentration of ozone in this region.
Of course, once the warm season returns and the currents shift these chemicals also spread through the atmosphere, resulting in further damage beyond their point of origin.
What does this mean to the layperson? Ozone damage is not limited by region. When CFCs become a problem in the atmosphere, they become a problem for everyone on the planet.
Ozone Depletion and Climate Change
One of the most common mistakes made by the layman when assessing atmospheric ozone depletion is this: the general consensus among many people is that ozone has “something to do” with climate change.
In this instance, it’s a separate issue from the effect of increasing CO2 levels which is proving to be a major culprit of climate change. Indeed, it’s an issue in and of its own.
Thankfully, as we noted, ozone depletion has been mostly handled at this point. While damage is going to continue as CFCs work through their cycles for a few decades the widespread usage of these chemicals is no longer a major concern.
It’s common for those who aren’t involved with issues to start conflating them, of course, since not everyone has the time to research both issues.
Make no mistake, both of these problems have some serious potential to devastate the world and the danger isn’t over when it comes to either, but regulations are making a serious dent in the release of ozone-depleting compounds.
Indeed, ozone depletion is much more related to smog issues than it is to climate change.
Of course, that doesn’t mean it should be ignored. Each issue which affects our interconnected environment needs to be handled, but fortunately in this instance regulation seems to have been quite effective and we’ve seen proof of recovery already.
As we noted, it’s likely to take decades without the use of ozone-depleting chemicals for a full recovery to take effect but this issue is one which proves that regulation can be effective on a large scale.
It’s a lot of information to take in, but if you take away nothing else then you should remember the following:
- Ozone depletion stems almost solely from man-made sources.
- While there was some initial resistance, eventually international measures were put into place to prevent further damage.
- These regulations are already showing their effects in lessened damage through the entirety of the atmosphere.
- When humanity cooperates, even global-scale problems can get fixed.